html/input: Escape dot in regular expression for email (#1841)
html/input: Escape dot in regular expression for email (#1841)

While the example suggests that it checked for `globex.com` email addresses, the
pattern accepted any character instead of the dot before `com`. So it matched
for example `foo@globexZcom`.

While it's harmless in our setting, we want to alert users that they have to
escape dots in regular expressions if they intend to only match dots, we set a
good example and escape the dot before `com`.
mdn/interactive-examples,mdn/interactive-examples,mdn/interactive-examples